The availability of 7 GHz of unlicensed spectrum in the 60 GHz band offers the potential for multi-Gigabit indoor wireless personal area networking (WPAN). Applications that require large bandwidth include uncompressed High Definition (HD) video streaming, fast file download from an airport kiosk (Sync & Go) and wireless display and docking, to name just a few. These applications cannot be supported over existing home networking solutions (IEEE 802.11a/b/g/n and WiMedia UWB) because the required data rates far exceed the capabilities of these networks.
A mmwave communication link is less robust than those at lower frequencies (e.g. 2.4 GHz and 5 GHz bands) because of its inherent isolation due to both oxygen absorption, which attenuates the signal over long range, and its short wavelength, which provides high attenuation through obstructions such as walls and ceilings. Thus, one of the biggest challenges for designing a high data rate radio system for the 60 GHz band is the limited link budget resulting from high path loss during radio propagation. On the one hand, it is preferable to employ directional antennas for high-speed point-to-point data transmission. On the other hand, a directional antenna pattern covering a wide range of angles to give omni-directional coverage is usually employed to aid in neighbor discovery and beam-steering decisions. A lower band channel (e.g. IEEE 802.11 WLAN in 2.4 GHz or 5 GHz bands or WiMedia UWB in 6 GHz band) may be used as an out-of-band (OOB) control channel providing robust transmission and coverage.
Spatial reuse is the ability of the network to support concurrent transmissions that depends on the network topology and individual transmission ranges. Devices performing directional transmissions can be separated in space such that certain pairs of devices can communicate simultaneously. However, in a traditional 60 GHz wireless personal area network (WPAN), the channel time is scheduled using Time Division Multiple Access (TDMA) technology that does not support parallel trasmissions. Channel time reservations are usually performed for each super-frame (the basic timing division for TDMA) and communicated in the beacon frame(s) sent on the control channel as seen in FIG. 1 at 100.
Thus, a strong need exists for techniques for spatial reuse in wireless personal area networks.
It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements.